DESCRIPTION OF FIGURES 



All figures were drawn with a Zeiss 1.5 mm. apochromatic objective, a no. 12 

 compensating ocular and projected with camera lucida to table level. Figures 

 as here reproduced give a magnification of 2100 diameters. Fixatives employed 

 are indicated by abbreviations: Strong Flemming's fluid (F); Flemming-urea 

 mixture (F-u); Hermann's fluid (H); Gilson-Carnoy's fluid (G. C); and Bouin 

 (B). 



PLATE 1 



SPERMATOGENESIS 



1 a, b. Spermatogonial prophase. (H) a and b are two successive sections 

 from the same nucleus. 



2 Spermatogonial metaphase {G. C). 



3 Spermatogonial metaphase (//). 



4 Spermatogonial resting stage (H). 



5 Pre-synaptic stage showing pro-chromosomes (F-u). 



6 Early leptotene stage (i^-w). 



7 Later leptotene stage (F-u). 



8 Synizesis (H). 



9 Synizesis, (later) F-u). 



10 Pachytene stage (early, release of contraction figure) (H). 



11 Pachytene stage (later, showing double threads) (H). 



12 Pachytene stage (still later showing quadripartite division of threads) 

 (H). 



13 Strepsitene stage (H). 



14 Diffuse stage (H). 



15 Prophase showing fragmentation of phasmasome (//). 



16 Prophase {G. C). 



17 First spermatocyte metaphase, showing the X-group centrally located. 



18 a, b, c. First spermatocyte anaphase. Figures are from one spindle; a, 

 showing upper ring of 13 autosomes and 1'; c, showing lower plate of 13 auto- 

 somes and gap opposite position of Y in a; and b, showing the intervening X- 

 element of 8 chromosomes. 



19 Second spermatocyte metaphase showing 14 chromosomes {F). 



20 Second spermatocyte metaphase showing 21 chromosomes {F). 



94 



